Cell hot-pressing shaping method, battery cell and cell hot-pressing shaping device

Abstract

Disclosed in the present application are a cell hot-pressing shaping method, a battery cell and a cell hot-pressing shaping device. The cell hot-pressing shaping method comprises the following steps: electrically connecting two positive electrode tabs (11) and / or two negative electrode tabs (21) of a bare cell structure (40) to a heating power source (50), so as to energize and heat the bare cell structure (40); and clamping, pressing and shaping the heated bare cell structure (40), so as to fix the shape contour of the bare cell structure (40). The present application aims to solve the problems of the energy utilization rate being low and the heating time being long when indirectly heating a bare cell structure by means of a hot-pressing plate, and the high temperature of the surface of the hot-pressing plate that abuts against the bare cell structure and the long time for which the hot-pressing plate abuts against the surface of the bare cell structure easily leading to the closing of separator pores.

Description

Battery cell hot pressing shaping method, battery cell and battery cell hot pressing shaping device

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on November 16, 2023, with application number 2023115320406 and invention name “Battery cell hot pressing and shaping method, battery cell and battery cell hot pressing and shaping device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application belongs to the field of lithium battery manufacturing technology, and in particular relates to a battery cell hot pressing and shaping method, a battery cell, and a battery cell hot pressing and shaping device. Background Art

[0003] Wound-type battery cells include bare cell structures, which are formed by stacking the positive electrode sheet, negative electrode sheet, and separator in a predetermined order and then winding them together. After unwinding, the wound bare cell structure is fluffy, making the positive and negative electrode sheets prone to slippage and difficult to assemble. Therefore, the wound bare cell structure typically requires hot or cold pressing to shape the bare cell into a fixed shape.

[0004] Currently, the application rate of hot pressing and shaping technology in the industry is higher than that of cold pressing and shaping technology. The related technology battery cell hot pressing device includes two sets of hot pressing components arranged opposite each other, with the hot pressing surfaces of the two sets of hot pressing components facing each other. The hot pressing components include hot pressing plates with a number of heating tubes connected to the sides of the hot pressing plates. The heating tubes heat the hot pressing plates. When the two sets of hot pressing plates move toward each other to clamp the bare battery cell structure, the hot pressing plates, heated by the heating tubes, complete the hot pressing process on the bare battery cell structure.

[0005] In summary, the battery cell hot pressing device of the related technology heats the bare battery cell structure indirectly through the hot pressing plate, which has low energy utilization and long heating time. In addition, the surface temperature of the hot pressing plate abutting the bare battery cell structure is high, and the time for the hot pressing plate to abut the surface of the bare battery cell structure is long, which can easily lead to closed pores in the diaphragm.

[0006] Summary of the Invention

[0007] The purpose of the embodiments of the present application is to provide a battery cell hot pressing and shaping method, a battery cell and a battery cell hot pressing and shaping device, including but not limited to solving the problem of indirect heating of the bare battery cell structure through the hot pressing plate, low energy utilization rate and long heating time, and the high surface temperature of the hot pressing plate abutting the bare battery cell structure and the long time that the hot pressing plate abuts the surface of the bare battery cell structure, which easily leads to closed pores in the diaphragm.

[0008] The technical solution adopted in the embodiment of this application is:

[0009] According to a first aspect of the present application, a method for hot pressing and shaping a battery cell is provided for hot pressing and shaping a bare battery cell structure. The method for hot pressing and shaping a battery cell comprises the following steps:

[0010] Electrically connecting two positive electrode tabs and / or two negative electrode tabs of the bare cell structure to a heating power source to electrically heat the bare cell structure;

[0011] The heated bare cell structure is clamped and pressed to fix the shape of the bare cell structure.

[0012] The battery cell hot pressing and shaping method provided in the embodiments of the present application heats the bare cell structure by directly energizing the electrode in the bare cell structure, causing the electrode to overcurrent and generate ohmic heat. This method can quickly and synchronously heat the inner and outer rings of the bare cell structure, resulting in short heating time, uniform heating, and good consistency in heating temperature distribution, and significantly improved energy utilization. In addition, the time that the pressing plate abuts the surface of the bare cell structure is shortened, thereby reducing the probability of diaphragm closure in the surface diaphragm of the bare cell structure and improving the product quality of the lithium battery.

[0013] In some embodiments of the present application, before performing the step of "electrically connecting two of the positive electrode tabs and / or two of the negative electrode tabs of the bare cell structure to a heating power source to electrically heat the bare cell structure," the steps of: stacking and composite-forming the positive electrode sheet, separator, and negative electrode sheet into a cell material roll, and winding the cell material roll to form the bare cell structure are performed. Rapidly winding the bare cell structure into a fluffy state prepares it for hot pressing and improves work efficiency.

[0014] In some embodiments of the present application, during the step of "electrically connecting two of the positive electrode tabs and / or two of the negative electrode tabs of the bare cell structure to a heating power source": the two positive electrode tabs are the two positive electrode tabs that are farthest apart when the bare cell structure is unfolded into a cell material roll; and / or the two negative electrode tabs are the two negative electrode tabs that are farthest apart when the bare cell structure is unfolded into a cell material roll. In this way, the ohmic resistance that can generate ohmic heat when the positive and / or negative electrode sheets are overcurrented is the largest, so that the heat generation efficiency of the ohmic heat generated by the positive and / or negative electrode sheets when overcurrent occurs is the highest, and the energy utilization rate is high.

[0015] In some embodiments of the present application, before performing the step of "winding the battery core material to form a bare battery core structure," the two positive tabs and / or the two negative tabs that need to be connected to the heating power source are die-cut to reserve the tab electrical connection ends. Because the tab electrical connection ends are longer than the tabs, the tab electrical connection ends are not interfered with by the remaining tabs when electrically connecting to the positive and negative poles of the heating power source, thereby completing the electrical connection more conveniently and quickly.

[0016] In some embodiments of the present application, when performing the step of "die-cutting the two positive electrode tabs and / or the two negative electrode tabs that need to be connected to the heating power source to reserve the tab connection ends," each positive electrode tab and each negative electrode tab are die-cut so that the contour shapes of each positive electrode tab and each negative electrode tab after die-cutting are consistent. Positive and negative electrode tabs with consistent shapes can be easily sorted separately, improving the efficiency of tab sorting.

[0017] In some embodiments of the present application, during the step of "winding the battery core material to form a bare battery core structure": the positive electrode tabs are aligned with each other, and there is a gap between the surfaces of two adjacent positive electrode tabs; and the negative electrode tabs are aligned with each other, and there is a gap between the surfaces of two adjacent negative electrode tabs. The alignment of the positive electrode tabs and the alignment of the negative electrode tabs are beneficial for quickly completing the electrical connection of the positive electrode tabs to the current collector of the positive electrode of the battery cell, and for quickly completing the electrical connection of the negative electrode tabs to the current collector of the negative electrode of the battery cell in the subsequent assembly process, thereby improving assembly efficiency. In addition, there is a gap between the surfaces of two adjacent positive electrode tabs and between the surfaces of two adjacent negative electrode tabs, that is, the two adjacent positive electrode tabs and the two adjacent negative electrode tabs are insulated from each other. In this way, when the two positive electrode tabs and / or the two negative electrode tabs are electrically connected to the positive pole and negative pole of the heating power supply and current flows, the current will inevitably flow through the conductor between the two tabs, so that the positive electrode sheet and / or the negative electrode sheet generates ohmic heat to efficiently heat the entire bare battery cell structure.

[0018] In some embodiments of the present application, after the step of "clamping and shaping the heated bare cell structure" is completed, the tab electrical end portions are trimmed. Trimming the tab electrical end portions ensures that the lengths of all positive and negative tabs are completely consistent, which facilitates the rapid electrical connection of each positive tab to the current collector of the positive electrode of the battery cell, and the rapid electrical connection of each negative tab to the current collector of the negative electrode of the battery cell, thereby improving assembly efficiency.

[0019] In some embodiments of the present application, during the step of "clamping and shaping the heated bare cell structure," the bare cell structure is clamped and shaped using a top-to-bottom clamping method. In this case, the first and second clamping plates used for clamping and shaping are positioned vertically opposite each other. The fluffy bare cell structure can be directly transferred and placed on the first clamping plate, simplifying the transfer process, saving time, and improving work efficiency.

[0020] In some embodiments of the present application, when performing the step of "electrically connecting two of the positive electrode tabs and / or two of the negative electrode tabs to a heating power source to electrically heat the bare cell structure", the heating time is 5s-10s. According to Ohm's law, ohmic heat Q = I 2 *R*t, achieves efficient heating of the bare cell structure, and the heating time is 5s-10s to heat the bare cell structure to the appropriate hot pressing temperature.

[0021] In some embodiments of the present application, when performing the step of "clamping and pressing the heated bare cell structure to fix the shape and contour of the bare cell structure," the time for clamping and pressing the bare cell structure is 5s-10s. The time for clamping and pressing the bare cell structure should not be too long. Selecting an appropriate pressure to clamp the bare cell structure for 5s-10s can obtain a bare cell structure with a fixed shape and contour, thereby reducing the risk of diaphragm closure caused by excessive clamping time.

[0022] In some embodiments of the present application, when performing the step of "clamping and pressing the heated bare cell structure to fix the shape and contour of the bare cell structure," the surface pressure of the clamping and pressing the bare cell structure is greater than or equal to 5 MPa. The pressure for clamping and pressing the bare cell structure should not be too high. Selecting an appropriate pressure of 5 MPa to clamp the bare cell structure can obtain a bare cell structure with a fixed shape and contour, thereby reducing the risk of diaphragm closure caused by excessive pressure.

[0023] In some embodiments of the present application, the interval time between executing the step of "electrically connecting two of the positive electrode tabs and / or two of the negative electrode tabs to a heating power source for electrical heating" and executing the step of "clamping and shaping the heated bare cell structure to fix the shape profile of the bare cell structure" is 0-10s. The heated bare cell structure is allowed to stand so that the overall temperature of the bare cell structure reaches the ideal temperature value for executing step S50. Since the temperature of the bare cell structure 40 is appropriate when executing step S50, the probability of diaphragm closure caused by the high temperature of the bare cell structure is effectively reduced, and the product quality of the hot-pressed bare cell structure is effectively improved.

[0024] According to another aspect of the present application, a battery cell is provided, wherein the battery cell comprises a bare cell structure that is hot-pressed and shaped using the aforementioned cell hot-pressing and shaping method.

[0025] According to another aspect of the present application, a battery cell hot pressing and shaping device is provided. The battery cell hot pressing and shaping device includes a shaping station, and the shaping station is provided with a driving mechanism, a first pressing plate, a second pressing plate and a heating power supply. The first pressing plate and the second pressing plate are arranged opposite to each other to clamp the bare battery cell structure. The driving mechanism is connected to the first pressing plate and / or the driving mechanism is connected to the second pressing plate. The heating power supply is used to energize and heat the bare battery cell structure. At this time, the first pressing plate and the second pressing plate used for clamping and shaping are arranged opposite to each other up and down, and the fluffy bare battery cell structure can be directly transferred and placed on the first pressing plate, which can simplify the transfer process of conveying the bare battery cell structure, save conveying time, and improve work efficiency. By directly energizing the electrode in the bare battery cell structure so that the electrode overcurrent generates ohmic heat to heat the bare battery cell structure, the inner and outer rings of the bare battery cell structure can be quickly and synchronously heated, with a short heating time, uniform heating, good heating temperature distribution consistency, and significantly improved energy utilization. In addition, the time that the pressure plate abuts against the surface of the bare cell structure is shorter, thereby reducing the probability of diaphragm closure occurring in the surface diaphragm of the bare cell structure and improving the product quality of the lithium battery.

[0026] In some embodiments of the present application, the battery cell hot pressing and shaping apparatus further includes a winding station, located upstream of the shaping station, for winding the battery cell material into a bare cell structure. Rapidly winding the bare cell structure into a fluffy state prepares it for hot pressing, improving work efficiency.

[0027] In some embodiments of the present application, the battery cell hot pressing and shaping device further includes a composite molding station and a die-cutting station, the die-cutting station being located upstream of the winding station, and the composite molding station being located upstream of the die-cutting station, the composite molding station being used to laminate and composite-mold the positive electrode sheet, the diaphragm, and the negative electrode sheet into a battery cell roll, and the die-cutting station being used to die-cut the positive electrode tabs and / or the negative electrode tabs on the battery cell roll, and to die-cut to obtain the tab electrical connection ends for electrical connection to the heating power supply. Since the tab electrical connection ends are extended in length based on the length of the tabs, the tab electrical connection ends will not be interfered with by the other tabs when electrically connected to the positive and negative electrodes of the heating power supply, thereby completing the electrical connection more conveniently and quickly.

[0028] In some embodiments of the present application, the shaping station is further provided with a cutting mechanism, which is used to cut the electrical ends of the tabs after the first and second pressing plates clamp the bare cell structure. Cutting off the electrical ends of the tabs ensures that the lengths of all positive tabs and all negative tabs are completely consistent, which facilitates the rapid electrical connection of each positive tab to the current collector of the positive electrode of the battery cell, and the rapid electrical connection of each negative tab to the current collector of the negative electrode of the battery cell, thereby improving assembly efficiency.

[0029] The embodiments of the present application have the following beneficial effects:

[0030] By directly energizing the electrode in the bare cell structure, causing overcurrent to generate ohmic heat, the bare cell structure can be heated quickly and simultaneously with the inner and outer rings. This results in short heating times, uniform heating, and consistent heating temperature distribution, significantly improving energy efficiency. Furthermore, the time the pressure plate abuts the surface of the bare cell structure is shortened, reducing the probability of diaphragm closure in the surface diaphragm of the bare cell structure and improving lithium battery product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or exemplary technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0032] FIG1 is a schematic flow chart of a method for hot pressing and shaping a battery cell according to an embodiment of the present application;

[0033] FIG2 is a schematic structural diagram of a bare cell structure, a first pressing plate, a second pressing plate, and a heating power supply in a cell hot pressing shaping method according to an embodiment of the present application;

[0034] FIG3 is a cross-sectional view of FIG2 ;

[0035] FIG4 is a schematic diagram of a bare cell structure to be hot-pressed and shaped in a method for hot-pressing and shaping a cell according to an embodiment of the present application;

[0036] FIG5 is a schematic structural diagram of a negative electrode sheet used in a bare cell structure to be hot-pressed and shaped in a cell hot-pressing and shaping method according to an embodiment of the present application;

[0037] FIG6 is a schematic structural diagram of a positive electrode sheet used in a bare cell structure to be hot-pressed and shaped in a cell hot-pressing and shaping method according to an embodiment of the present application;

[0038] FIG7 is a schematic structural diagram of a negative electrode tab connected to an electrical end in FIG5 ;

[0039] FIG8 is a schematic diagram of the arrangement of a composite molding station, a die-cutting station, a winding station, and a shaping station of a battery cell hot pressing and shaping device according to an embodiment of the present application;

[0040] FIG9 is a schematic diagram of the exploded structure of a battery cell according to an embodiment of the present application.

[0041] Among them, the reference numerals in the figures are:

[0042] 10. Positive electrode sheet; 11. Positive electrode tab; 12. First gap;

[0043] 20. Negative electrode sheet; 21. Negative electrode tab; 22. Negative electrode tab electrical connection end; 23. Second gap;

[0044] 30. Diaphragm; 31. First diaphragm; 32. Second diaphragm;

[0045] 40. Bare cell structure;

[0046] 50. Heating power supply; 51. Positive pole of power supply; 52. Negative pole of power supply;

[0047] 61. First pressing plate; 62. Second pressing plate;

[0048] 71. Composite molding station; 72. Die cutting station; 73. Winding station; 74. Shaping station;

[0049] 100. Battery cell; 101. End cap; 102. Electrode terminal; 103. Housing; 104. Current collector; 105. Liquid capsule. DETAILED DESCRIPTION

[0050] The following describes in detail embodiments of the present application, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0051] In the description of this application, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0052] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified with "first," "second," etc., may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0053] In this application, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components or interactions between two components. Those skilled in the art will understand the specific meanings of these terms in this application based on specific circumstances.

[0054] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0055] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0056] Currently, market developments indicate that the application of power batteries, particularly lithium batteries, is becoming increasingly widespread. Lithium batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but are also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric vehicles, as well as in police equipment, military equipment, and aerospace. As the application of lithium batteries continues to expand, market demand is also growing.

[0057] The production of lithium batteries requires a series of processes, including electrode assembly, winding, and shaping, to form lithium battery cells. These cells are then assembled into lithium batteries. The shaping process reshapes the fluffy, wound bare cell structure to stabilize its shape and contour, thereby resolving the issue of slippage and difficulty in assembly of the positive and negative electrodes in the fluffy bare cell structure.

[0058] The composite process refers to the roll-combination of the positive electrode sheet, separator and negative electrode sheet into a cell material roll for winding the bare cell structure.

[0059] The winding process refers to winding the composite formed battery cell material roll to form a bare battery cell structure semi-finished product. At this time, the bare battery cell structure semi-finished product formed by winding is in a fluffy state, the shape outline of the bare battery cell structure is not fixed, and the positive and negative electrodes in the bare battery cell structure are easy to slip and difficult to assemble.

[0060] The shaping process refers to the use of hot pressing or cold pressing to clamp and press the fluffy bare cell structure to fix the shape contour of the bare cell structure, thereby solving the problem that the positive and negative electrode sheets in the fluffy bare cell structure are easy to slip and difficult to assemble, which is conducive to improving the assembly accuracy and efficiency of subsequent assembly to form battery cells.

[0061] In related technologies, the shaping process usually adopts hot pressing or cold pressing. Among them, the hot pressing process is more popular in the industry than the cold pressing process. Currently, the hot pressing process generally involves heating the fluffy bare cell structure through a preheating tunnel furnace, and then transferring the heated bare cell structure to a press plate for clamping and shaping; or, heating the press plate to a high temperature, transferring heat to the fluffy bare cell structure through the press plate to heat the bare cell structure, and then applying pressure to the heated bare cell structure to achieve hot pressing shaping.

[0062] However, whether the fluffy bare cell structure is heated by a preheating tunnel furnace or by a high-temperature pressing plate, the heating time is relatively long, the energy utilization rate is low, and the temperature distribution of the inner and outer rings of the bare cell structure is uneven. Moreover, when the fluffy bare cell structure is heated and hot-pressed by a high-temperature pressing plate, the surface temperature of the hot pressing plate in contact with the surface of the bare cell structure is high, and the time the hot pressing plate in contact with the surface of the bare cell structure is long, which can easily lead to the formation of diaphragm closure on the surface of the bare cell structure, thereby affecting the electrolyte's infiltration effect on the electrode and affecting the product quality of the lithium battery.

[0063] Diaphragm closed-pore means that a diaphragm is required to insulate and isolate the positive and negative electrodes. The diaphragm has micropores that allow the electrolyte to pass through, allowing the electrolyte to infiltrate the positive and negative electrodes, thereby allowing the positive and negative electrodes and the electrolyte to undergo normal electrochemical reactions to generate electricity. Therefore, it is necessary to ensure that the diaphragm's micropores are not closed. If the diaphragm's micropores are closed, especially if part or all of the micropores of the outer ring diaphragm of the bare cell structure are closed, it will seriously affect the quality of the bare cell structure product. As the name suggests, diaphragm closed-pore means that the diaphragm's micropores are closed and the electrolyte cannot pass through, which is an undesirable phenomenon that affects product quality.

[0064] Based on the above considerations, in order to solve the problems in the current technology of long heating time for bare cell structures, low energy utilization, uneven temperature distribution of the inner and outer rings of the bare cell structures, and easy closure of the diaphragm, the embodiment of the present application designs a cell hot pressing and shaping method for hot pressing and shaping the bare cell structure so that the shape contour of the bare cell structure in a fluffy state is fixed. The cell hot pressing and shaping method provided by the embodiment of the present application achieves rapid heating of the bare cell structure by directly energizing the electrode in the bare cell structure so that the electrode overcurrent generates ohmic heat to heat the bare cell structure. Moreover, the ohmic heat generated by the overcurrent of the electrode can quickly and synchronously heat the inner and outer rings of the bare cell structure, with short heating time, uniform heating, good heating temperature distribution consistency, and significantly improved energy utilization. In this way, during clamping and shaping, the clamping time of the pressure plate on the bare battery cell structure can be shortened compared to the clamping time of the current technology, that is, the time that the pressure plate abuts the surface of the bare battery cell structure is shorter, thereby reducing the probability of diaphragm closure in the surface diaphragm of the bare battery cell structure and improving the product quality of the lithium battery.

[0065] In addition, the embodiments of the present application also design a battery cell hot pressing and shaping device for implementing the battery cell hot pressing and shaping method designed in the embodiments of the present application.

[0066] The battery cell hot pressing shaping method and the corresponding battery cell hot pressing shaping device designed in the embodiment of the present application are suitable for the preparation and production of wound lithium batteries, wherein the wound lithium batteries include but are not limited to wound square lithium batteries and wound cylindrical lithium batteries. In addition, the bare battery cell structure hot-pressed by the battery cell hot pressing shaping method disclosed in the embodiment of the present application is used to prepare and produce battery monomers, and the battery monomers are used to prepare and produce lithium batteries. The prepared lithium batteries can be used for but not limited to mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Among them, electric toys can include fixed or mobile electric toys, for example, game consoles, electric car toys, electric ship toys and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles and spacecraft, etc.

[0067] According to some embodiments of the present application, referring to FIG1 and FIG2 , the battery cell hot pressing shaping method includes the following core steps S40 and S50:

[0068] Step S40: electrically connecting two of the positive electrode tabs 11 and / or two of the negative electrode tabs 21 of the bare cell structure 40 to the heating power source 50 to electrically heat the bare cell structure 40. This can be done by electrically connecting only the positive electrode tabs 11 to the heating power source 50, so that the positive electrode sheet 10 generates ohmic heat when the positive electrode sheet 10 is overcurrent. Since the positive electrode sheet 10, the separator 30 and the negative electrode sheet 20 are in contact with each other in the bare cell structure 40, the ohmic heat generated by the positive electrode sheet 10 can quickly transfer heat to the separator 30 and the negative electrode sheet 20, thereby allowing the bare cell structure 40 to be quickly and evenly heated as a whole, with high energy utilization. Alternatively, only the negative electrode tab 21 may be electrically connected to the heating power source 50, so that the negative electrode sheet 20 generates ohmic heat when the negative electrode sheet 20 is overcurrented. Since the positive electrode sheet 10, the diaphragm 30 and the negative electrode sheet 20 are in contact with each other in the bare cell structure 40, the ohmic heat generated by the negative electrode sheet 20 can quickly transfer heat to the diaphragm 30 and the positive electrode sheet 10, so that the entire bare cell structure 40 is quickly and evenly heated, with high energy utilization. Alternatively, both the positive electrode tab 11 and the negative electrode tab 21 may be electrically connected to the heating power source 50, so that both the positive electrode sheet 10 and the negative electrode sheet 20 generate ohmic heat when overcurrented, so that the entire bare cell structure 40 is quickly and evenly heated, with higher heating efficiency, relatively higher energy utilization, and better heating uniformity.

[0069] Step S50: The heated bare cell structure 40 is clamped and pressed to fix the shape of the bare cell structure 40. In some embodiments of the present application, the clamping and pressing process produces a wound square bare cell structure 40, which is then assembled into a square lithium battery.

[0070] "Positive electrode sheet 10 overcurrent" and "negative electrode sheet 20 overcurrent" mean that: the positive electrode sheet 10 and the negative electrode sheet 20 themselves have ohmic resistance, and the positive electrode sheet 10 and the negative electrode sheet 20 can be used as resistive heating devices. By electrically connecting the positive electrode sheet 10 to the positive power supply 51 and the negative power supply 52 of the heating power supply 50 to form a loop, and by electrically connecting the negative electrode sheet 20 to the positive power supply 51 and the negative power supply 52 of the heating power supply 50 to form another loop, when the loop is closed, the current passes through the positive electrode sheet 10 and the negative electrode sheet 20, and the positive electrode sheet 10 and the negative electrode sheet 20 generate ohmic heat.

[0071] Ohmic heat: According to Ohm's law, when current passes through a conductor, due to the conductor's resistance, the current will generate heat in the conductor. Moreover, ohmic heat, that is, the heat generated in the conductor, is proportional to the conductor's resistance, the strength of the current passing through it, and the time the current passes through it. The calculation formula is: Q = I 2*R*t, where Q represents the amount of heat generated (in joules), I represents the current strength (in amperes), R represents the resistance of the conductor (in ohms), and t represents the time the current flows (in seconds).

[0072] In some embodiments of the present application, referring to FIG1 , before executing step S40, that is, before executing “electrically connecting two of the positive electrode tabs 11 and / or two of the negative electrode tabs 21 of the bare cell structure 40 to the heating power source 50”, it is necessary to complete the preparatory work, that is, it is necessary to complete step S10 and step S30. Specifically, the positive electrode sheet 10, the diaphragm 30 and the negative electrode sheet 20 are stacked and composite-formed into a cell material roll, that is, step S10 in the cell hot pressing shaping method is completed: the positive electrode sheet 10, the diaphragm 30 and the negative electrode sheet 20 are composite-formed into a cell material roll. Among them, in the composite-formed cell material roll, as shown in FIG3 , the diaphragm 30 includes a first diaphragm 31 and a second diaphragm 32, and the first diaphragm 31, the positive electrode sheet 10, the second diaphragm 32 and the negative electrode sheet 20 are stacked in sequence and composite-rolled to form a cell material roll. In addition, the positive electrode sheet 10 has a plurality of positive electrode tabs 11, and two adjacent positive electrode tabs 11 are spaced apart. The negative electrode sheet 20 has a plurality of negative electrode tabs 21, and two adjacent negative electrode tabs 21 are spaced apart. The plurality of positive electrode tabs 11 and the plurality of negative electrode tabs 21 extend beyond the edge of the separator 30. And the completion step S30 is executed: the battery core material roll is wound to form a bare battery core structure 40. After the completion step S30 is executed, the battery core material roll is wound into a semi-finished product of the bare battery core structure 40, and the semi-finished product of the bare battery core structure 40 is the bare battery core structure 40 in a fluffy state.

[0073] Alternatively, the fluffy bare cell structure 40 is a purchased cell raw material, and then steps S40 and S50 can be directly performed on the fluffy bare cell structure 40 without performing any preparation work on the purchased bare cell structure 40.

[0074] During the preparatory work, as shown in Figures 5 and 6, the preparatory work includes, but is not limited to, die-cutting each positive electrode tab 11 and each negative electrode tab 21 so that the contour shapes of each positive electrode tab 11 and each negative electrode tab 21 after die-cutting are consistent. In other words, after completing step S10 of "compositely forming the positive electrode sheet 10, separator 30, and negative electrode sheet 20 into a battery core material roll," the positive electrode tab 11 of the compositely formed positive electrode sheet 10 and the negative electrode tab 21 of the negative electrode sheet 20 are die-cut to obtain the positive electrode tab 11 and negative electrode tab 21 of the predetermined shape. In addition, the positive electrode tab 11 and negative electrode tab 21 with the same shape can be easily sorted separately, improving the efficiency of the tab sorting work.

[0075] Moreover, in some embodiments of the present application, before executing step S30, that is, before executing "winding the battery core material to form a bare battery core structure 40", it is also necessary to execute step S20: die-cut the two positive electrode tabs 11 and / or the two negative electrode tabs 21 that need to be connected to the heating power supply 50 to reserve the tab electrical connection ends. When only the positive electrode tabs 11 are electrically connected to the heating power supply 50, only the two positive electrode tabs 11 on the positive electrode sheet 10 that need to be used to electrically connect to the heating power supply 50 are die-cut to reserve the positive electrode tab electrical connection ends, and the remaining positive electrode tabs 11 do not need to reserve the positive electrode tab electrical connection ends (that is, these positive electrode tabs 11 are directly die-cut to form the final shape of the positive electrode tabs 11 of the bare battery core structure 40). When only the negative electrode tabs 21 are electrically connected to the heating power source 50, only the two negative electrode tabs 21 on the negative electrode sheet 20 that need to be electrically connected to the heating power source 50 are die-cut to reserve the negative electrode tab electrical connection end 22, as shown in Figure 5, and the remaining negative electrode tabs 21 do not need to reserve the negative electrode tab electrical connection end 22 (that is, these negative electrode tabs 21 are directly die-cut to form the final shape of the negative electrode tabs 21 of the bare battery cell structure 40). When both the positive electrode tabs 11 and the negative electrode tabs 21 are electrically connected to the heating power source 50, the two positive electrode tabs 11 that need to be electrically connected to the heating power source 50 are die-cut to reserve the positive electrode tab electrical connection end and the two negative electrode tabs 21 that need to be electrically connected to the heating power source 50 are die-cut to reserve the negative electrode tab electrical connection end 22, and the remaining positive electrode tabs 11 and negative electrode tabs 21 are directly die-cut to form the final shape of the positive electrode tabs 11 and negative electrode tabs 21 of the bare battery cell structure 40.

[0076] By die-cutting, the electrical connection end of the tab is reserved. When the positive tab 11 and / or the negative tab 21 is electrically connected to the heating power supply 50, since the length of the tab electrical connection end is extended based on the length of the tab, the tab electrical connection end will not be interfered with by the other tabs when electrically connected to the positive power supply 51 and the negative power supply 52 of the heating power supply 50, thereby completing the electrical connection more conveniently and quickly, as shown in Figure 2.

[0077] Referring to Figures 1, 2, 4 and 5, in some embodiments of the present application, during the process of performing step S40, that is, during the process of "electrically connecting two of the positive electrode tabs 11 and / or two of the negative electrode tabs 21 to the heating power source 50": when only the positive electrode tabs 11 are electrically connected to the heating power source 50, the two positive electrode tabs 11 are the two positive electrode tabs 11 that are farthest apart when the bare battery core structure 40 is unfolded into a battery core material roll; when only the negative electrode tabs 21 are electrically connected to the heating power source 50, the two positive electrode tabs 11 are the two positive electrode tabs 11 that are farthest apart when the bare battery core structure 40 is unfolded into a battery core material roll; When the heating power source 50 is connected, the two negative electrode tabs 21 are the two negative electrode tabs 21 that are farthest apart when the bare cell structure 40 is unfolded into a cell material roll; or, when both the positive electrode tab 11 and the negative electrode tab 21 are electrically connected to the heating power source 50, the two positive electrode tabs 11 are the two positive electrode tabs 11 that are farthest apart when the bare cell structure 40 is unfolded into a cell material roll, and the two negative electrode tabs 21 are the two negative electrode tabs 21 that are farthest apart when the bare cell structure 40 is unfolded into a cell material roll. In this way, in the process of using ohmic heat to heat the bare cell structure 40, energy utilization can be effectively improved.

[0078] When the two positive electrode tabs 11 electrically connected to the heating power source 50 are selected as the two positive electrode tabs 11 that are farthest apart when the bare cell structure 40 is unfolded into a cell material roll, the ohmic resistance that can generate ohmic heat when the positive electrode sheet 10 is overcurrented is the largest, the heat generation efficiency of the positive electrode sheet 10 generating ohmic heat when the overcurrent is the highest, and the energy utilization rate is high. Similarly, when the two negative electrode tabs 21 electrically connected to the heating power source 50 are selected as the two negative electrode tabs 21 that are farthest apart when the bare cell structure 40 is unfolded into a cell material roll, the ohmic resistance that can generate ohmic heat when the negative electrode sheet 20 is overcurrented is the largest, the heat generation efficiency of the negative electrode sheet 20 generating ohmic heat when the overcurrent is the highest, and the energy utilization rate is high.

[0079] In addition, in some embodiments of the present application, the two positive electrode tabs 11 and / or the two negative electrode tabs 21 electrically connected to the heating power source 50 may not be the two positive electrode tabs 11 and / or the two negative electrode tabs 21 that are farthest apart when the bare cell structure 40 is unfolded into a cell material roll. For example, when the bare cell structure 40 is unfolded into a cell material roll, the cell material roll is divided into equal parts, and then any positive electrode tab 11 and / or negative electrode tab 21 is selected from the divided cell material roll. For example, if the equal parts are divided into two equal parts, in this case, the two positive electrode tabs 11 and / or the two negative electrode tabs 21 electrically connected to the heating power source 50 can be selected from the positive electrode tabs 11 and / or the negative electrode tabs 21 that are relatively centrally located on any equal part of the cell material roll. For another example, if the equal parts are divided into three equal parts, the positive electrode tabs 11 and / or the negative electrode tabs 21 that are close to the equal division position of the adjacent two equal parts of the cell material roll can be selected. For example, if the battery cell is divided into four equal parts, the positive electrode tab 11 and / or the negative electrode tab 21 in the relatively central position on any section of the battery cell material roll can be selected. In this way, the two positive electrode tabs 11 and / or the negative electrode tab 21 electrically connected to the heating power supply 50 are selected. By generating ohmic heat by overcurrent on the positive electrode sheet 10 and / or the negative electrode sheet 20 to heat the bare battery cell structure 40, not only can efficient heating of the bare battery cell structure 40 be achieved, but also the bare battery cell structure 40 can be heated uniformly and consistently, and the energy utilization rate is effectively improved.

[0080] In some embodiments of the present application, referring to FIG. 2 and FIG. 4 , during step S30 , i.e., during the process of “winding the battery core material to form a bare battery core structure 40 ,” the positive electrode tabs 11 are aligned with each other, with a gap between the surfaces of two adjacent positive electrode tabs 11, i.e., a first gap 12 is formed between the surfaces of two adjacent positive electrode tabs 11, as shown in FIG. 4 ; and the negative electrode tabs 21 are aligned with each other, with a gap between the surfaces of two adjacent negative electrode tabs 21, i.e., a second gap 23 is formed between the surfaces of two adjacent negative electrode tabs 21, as shown in FIG. In the bare battery core structure 40 , the alignment of the positive electrode tabs 11 and the alignment of the negative electrode tabs 21 facilitates the rapid electrical connection of the positive electrode tabs 11 to the current collector 104 of the positive electrode of the battery cell 100 and the rapid electrical connection of the negative electrode tabs 21 to the current collector 104 of the negative electrode of the battery cell 100 in the subsequent assembly process, thereby improving assembly efficiency. The semi-finished product of the wound bare cell structure 40, i.e., the fluffy bare cell structure 40, has a first gap 12 between the surfaces of two adjacent positive electrode tabs 11 thereon, that is, the two adjacent positive electrode tabs 11 are insulated from each other. Thus, when two of the positive electrode tabs 11 are electrically connected to the positive power supply 51 and the negative power supply 52 of the heating power supply 50 and current is passed through, the current will inevitably flow through the conductor between the two positive electrode tabs 11, so that the positive electrode sheet 10 generates ohmic heat to heat the entire bare cell structure 40. Similarly, the surfaces of two adjacent negative electrode tabs 21 on the fluffy bare cell structure 40 have a second gap 23 between them, that is, the two adjacent negative electrode tabs 21 are insulated from each other. Thus, when two of the negative electrode tabs 21 are electrically connected to the positive power supply 51 and the negative power supply 52 of the heating power supply 50 and current is passed through, the current will inevitably flow through the conductor between the two negative electrode tabs 21, so that the negative electrode sheet 20 generates ohmic heat to heat the entire bare cell structure 40.

[0081] In addition, in some embodiments of the present application, in the bare cell structure 40 formed by winding, the positive electrode tabs 11 may be misaligned, and / or the negative electrode tabs 21 may also be misaligned. In the subsequent assembly process, the positive electrode tabs 11 and the negative electrode tabs 21 need to be classified, and then the classified positive electrode tabs 11 are electrically connected to the positive electrode current collector 104 of the battery cell 100, and the classified negative electrode tabs 21 are electrically connected to the negative electrode current collector 104 of the battery cell 100, and it is ensured that the positive electrode current collector 104 and the negative electrode current collector 104 are insulated from each other.

[0082] As shown in FIG1 , in some embodiments of the present application, after executing step S50, that is, after executing “clamping and shaping the heated bare cell structure 40”, the shape outline of the bare cell structure 40 is fixed, and then step S60 is executed: the electrical connection ends of the tabs are cut, that is, the two positive electrode tab electrical connection ends are cut off, and / or the two negative electrode tab electrical connection ends 22 are cut off. In this way, the lengths of all the positive electrode tabs 11 are completely consistent, and / or the lengths of all the negative electrode tabs 21 are completely consistent. In this way, it is beneficial to quickly complete the electrical connection of each positive electrode tab 11 to the current collector 104 of the positive electrode of the battery cell 100, and quickly complete the electrical connection of each negative electrode tab 21 to the current collector 104 of the negative electrode of the battery cell 100, thereby improving assembly efficiency.

[0083] Taking the die-cut reserved negative electrode tab connection end 22 as an example for explanation, the die-cut reserved positive electrode tab connection end can refer to the negative electrode tab connection end 22. As shown in Figure 7, the negative electrode tab 21 is a trapezoidal shape that gradually shrinks from the negative electrode sheet 20 to the free end. In the final shape of the negative electrode tab 21, the width of the free end of the negative electrode tab 21 is D, that is, the width of the starting end of the negative electrode tab connection end 22 is D, and the length of the negative electrode tab connection end 22 is H. In addition, a circular through-hole is provided on the negative electrode tab connection end 22 to facilitate electrical connection to the negative power supply 52 of the heating power supply 50. The diameter of the circular through-hole is d. In some specific embodiments of the present application, the outer dimensions of the negative electrode tab connection end 22 are: D is 20 mm, H is 30 mm, and d is 6 mm.

[0084] In other embodiments of the present application, after the "clamping and shaping of the heated bare cell structure 40" is completed, the two positive electrode tabs and / or the two negative electrode tabs may be retained. When each positive electrode tab 11 is electrically connected to the positive electrode current collector 104 of the battery cell 100, the two positive electrode tabs and the electrical connection ends are bent and covered with the ends of the remaining positive electrode tabs 11, and then all the positive electrode tabs 11 are electrically connected as a whole to the positive electrode current collector 104 of the battery cell 100. Similarly, when each negative electrode tab 21 is electrically connected to the negative electrode current collector 104 of the battery cell 100, the two negative electrode tabs and the electrical connection ends 22 are bent and covered with the ends of the remaining negative electrode tabs 21, and then all the negative electrode tabs 21 are electrically connected as a whole to the negative electrode current collector 104 of the battery cell 100.

[0085] As shown in FIG3 , in some embodiments of the present application, during the execution of step S50, that is, during the execution of “clamping and shaping the heated bare cell structure 40”: the bare cell structure 40 is clamped and shaped by clamping from top to bottom. That is to say, at this time, the first pressing plate 61 and the second pressing plate 62 used for clamping and shaping are arranged to face each other from top to bottom. After completing “step S30: winding the cell material to form a bare cell structure 40”, the fluffy bare cell structure 40 can be directly transferred and placed on the first pressing plate 61, as shown in FIG3 . Then execute “step S40: electrically connecting two of the positive electrode tabs 11 and / or two of the negative electrode tabs 21 to the heating power source 50 for electrical heating”. The first pressing plate 61 and the second pressing plate 62 are arranged vertically opposite each other. During the clamping and pressing operation, only the first pressing plate 61 can move upward toward the second pressing plate 62, or only the second pressing plate 62 can move downward toward the first pressing plate 61, or the first pressing plate 61 and the second pressing plate 62 can move toward each other simultaneously, thereby clamping and shaping the heated, fluffy bare cell structure 40. In addition, the first pressing plate 61 can be used as a supporting member for the fluffy bare cell structure 40, which can simplify the transfer process of the bare cell structure 40, save transportation time, and improve work efficiency.

[0086] In some embodiments of the present application, when executing step S40, that is, when executing "electrically connecting two of the positive electrode tabs 11 and / or two of the negative electrode tabs 21 to the heating power source 50 for electrical heating", the heating time is 5s-10s, so as to fully heat the entire bare cell structure 40. Moreover, when executing step S50, that is, when executing "clamping and shaping the heated bare cell structure 40 to fix the shape and contour of the bare cell structure 40", the time for clamping the bare cell structure 40 is 5s-10s, so as to clamp and fix the shape and contour of the bare cell structure 40. Among them, in some embodiments of the present application, when executing step S50, that is, when executing "clamping and shaping the heated bare cell structure 40 to fix the shape contour of the bare cell structure 40", the surface pressure of clamping the bare cell structure 40 is greater than or equal to 5MPa, and the fluffy bare cell structure 40 is clamped and shaped with sufficient pressure so that the bare cell structure 40 is clamped to form a shape contour of a predetermined size.

[0087] In some specific embodiments of the present application, the heating power supply 50 outputs a current I of 70A-100A to the positive electrode sheet 10 and / or the negative electrode sheet 20, for example, specifically 85A, and the current-carrying time of the positive electrode sheet 10 and / or the negative electrode sheet 20 is 10s (i.e., the heating time is 10s), thereby heating the fluffy bare cell structure 40 to about 90°C. At this time, the temperature difference between the inner ring and the outer ring of the fluffy bare cell structure 40 is about 2°C, and the bare cell structure 40 is heated uniformly as a whole, and the heating consistency is good. In addition, a surface pressure of 5MPa is used between the first pressing plate 61 and the second pressing plate 62 to clamp and shape the fluffy bare cell structure 40, and the clamping and shaping time is 7s. In this way, there is no undesirable phenomenon of the pole piece opening (especially the inner ring pole piece opening) or the diaphragm closed hole in the bare cell structure 40 after hot pressing and shaping, which improves the product yield of the bare cell structure 40.

[0088] Pole opening means that when the fluffy bare cell structure 40 is clamped by the first pressure plate 61 and the second pressure plate 62, the bare cell structure 40 is subjected to uneven pressure, which causes the inner and outer ring pole pieces to deform inconsistently during the clamping process. The edge areas of the pole pieces will bend outward and appear to be open, especially the edge areas of the inner ring pole pieces will bend outward and appear to be open. This is called pole opening, which is an undesirable phenomenon that affects product quality.

[0089] In some embodiments of the present application, between executing step S40 and executing step S50, that is, between executing "electrically connecting two of the positive electrode tabs 11 and / or two of the negative electrode tabs 21 to the heating power source 50 to electrically heat the bare cell structure 40" and executing "clamping and shaping the heated bare cell structure 40 to fix the shape profile of the bare cell structure 40", the interval time between the two steps is 0-10s. Since when executing step S40, the temperature at which different bare cell structures 40 are heated is not always the ideal temperature value for executing step S50, the overall temperature of some bare cell structures 40 is sometimes slightly higher than the ideal temperature value for executing step S50. At this time, the heated bare cell structure 40 is left to stand, so that the overall temperature of the bare cell structure 40 reaches the ideal temperature value for executing step S50. This can effectively improve the product quality of the bare cell structure 40 with a fixed shape contour obtained by the clamping and shaping in step S50. Since the temperature of the bare cell structure 40 is appropriate when executing step S50, the probability of diaphragm closure caused by the high temperature of the bare cell structure 40 is effectively reduced, and the product quality of the bare cell structure 40 formed by hot pressing is effectively improved.

[0090] In a specific embodiment of the present application, the battery cell hot pressing shaping method provided by the design includes the following steps in sequence:

[0091] Step S10: The positive electrode sheet 10, the separator 30 and the negative electrode sheet 20 are composite-formed into a battery core roll;

[0092] Step S20: Die-cut the two positive electrode tabs 11 and / or the two negative electrode tabs 21 that need to be connected to the heating power source 50 to reserve the tab power connection ends;

[0093] Step S30: Winding the battery core material to form a bare battery core structure 40;

[0094] Step S40: electrically connecting two of the positive electrode tabs 11 and / or two of the negative electrode tabs 21 of the bare cell structure 40 to the heating power source 50 to electrically heat the bare cell structure 40;

[0095] Step S50: clamping and shaping the heated bare cell structure 40 to fix the shape of the bare cell structure 40;

[0096] Step S60: cutting the electrical end of the tab.

[0097] Among them, during the execution of the specific embodiment of the present application, step S40 is to heat the entire bare cell structure 40 by passing an overcurrent through the negative electrode sheet 20 to generate ohmic heat. Therefore, when executing step S20, only the two negative electrode tabs 21 of the negative electrode sheet 20 that are electrically connected to the heating power supply 50 are die-cut to reserve the negative electrode tab power connection end 22, and the two negative electrode tabs 21 that are electrically connected to the positive power supply 51 and the negative power supply 52 of the heating power supply 50 are the two negative electrode tabs 21 that are farthest apart when the bare cell structure 40 is unfolded into a cell material roll. When executing step S40, the heating power supply 50 outputs a current I of 85A to the negative electrode sheet 20, and the current-carrying time of the negative electrode sheet 20 is 10s (that is, the heating time is 10s), thereby heating the fluffy bare cell structure 40 to about 90°C. Furthermore, when executing step S50 , the first pressing plate 61 and the second pressing plate 62 are clamped and pressed to shape the fluffy bare cell structure 40 with a surface pressure of 5 MPa, and the clamping and shaping time is 7 seconds.

[0098] According to another aspect of the embodiment of the present application, a battery cell hot pressing and shaping device is designed and provided, as shown in Figure 8. Of the two omission symbols shown in Figure 8, one represents the omission of the workstation and equipment in the previous process, and the other represents the omission of the workstation and equipment in the subsequent process. The battery cell hot pressing and shaping device designed in the embodiment of the present application includes a shaping station 74. As shown in Figures 2 and 3, the shaping station 74 is provided with a driving mechanism (not shown), a first pressing plate 61, a second pressing plate 62 and a heating power supply 50. Specifically, the first pressing plate 61 and the second pressing plate 62 are arranged opposite to each other to clamp the bare battery cell structure 40, the driving mechanism is connected to the first pressing plate 61 and / or the driving mechanism is connected to the second pressing plate 62, and the heating power supply 50 is used to electrically heat the bare battery cell structure 40.

[0099] In some embodiments of the present application, the first pressing plate 61 and the second pressing plate 62 are arranged vertically opposite each other. The first pressing plate 61 is used to place the bare cell structure 40. The fluffy bare cell structure 40 can be directly transferred and placed on the first pressing plate 61. In other words, using the first pressing plate 61 as a supporting component for the fluffy bare cell structure 40 can simplify the transfer process of the bare cell structure 40, save transportation time, and improve work efficiency.

[0100] In some embodiments of the present application, the driving mechanism may be driven only by the first pressing plate 61 , that is, the driving mechanism drives the first pressing plate 61 to move toward the second pressing plate 62 , and at this time the second pressing plate 62 is fixed.

[0101] In some embodiments of the present application, the driving mechanism may be driven only by the second pressing plate 62 , that is, the driving mechanism drives the second pressing plate 62 to move toward the first pressing plate 61 , and at this time the first pressing plate 61 is fixed.

[0102] In some embodiments of the present application, the driving mechanism is driven and connected to the first pressing plate 61 and the second pressing plate 62, that is, the driving mechanism drives the first pressing plate 61 and the second pressing plate 62 to move toward each other simultaneously to clamp and heat the bare cell structure 40, so that the bare cell structure 40 in a fluffy state is clamped and shaped into a fixed shape contour.

[0103] As shown in Figures 8 and 3 , the cell hot pressing and shaping apparatus further includes a winding station 73. Located upstream of the shaping station 74, the winding station 73 is used to wind the cell material to form a bare cell structure 40. The wound bare cell structure 40 is now fluffy and is a semi-finished product.

[0104] As shown in Figures 5 to 8, the battery cell hot pressing and shaping device also includes a composite molding station 71 and a die-cutting station 72. The composite molding station 71 is located upstream of the die-cutting station 72 and is used to laminate and compositely mold the positive electrode sheet 10, the separator 30, and the negative electrode sheet 20 into a battery cell roll. The die-cutting station 72 is located upstream of the winding station 73 and is used to die-cut the positive electrode tabs 11 and / or the negative electrode tabs 21 on the battery cell roll and die-cut to obtain the tab electrical connection ends for electrical connection to the heating power supply 50. By die-cutting, the electrical connection end of the tab is reserved. When the positive tab 11 and / or the negative tab 21 is electrically connected to the heating power supply 50, since the length of the tab electrical connection end is extended based on the length of the tab, the tab electrical connection end will not be interfered with by the other tabs when electrically connected to the positive power supply 51 and the negative power supply 52 of the heating power supply 50, thereby completing the electrical connection more conveniently and quickly, as shown in Figure 2.

[0105] In some embodiments of the present application, the shaping station 74 is further provided with a cutting mechanism (not shown). After the first pressing plate 61 and the second pressing plate 62 clamp the bare cell structure 40, the cutting mechanism is used to cut the electrical connection ends of the tabs, that is, cut off the two positive pole tab electrical connection ends, and / or cut off the two negative pole tab electrical connection ends 22. In this way, the lengths of all the positive pole tabs 11 are completely consistent, and / or the lengths of all the negative pole tabs 21 are completely consistent. In this way, it is beneficial to quickly complete the electrical connection of each positive pole tab 11 to the current collector 104 of the positive electrode of the battery cell 100, and quickly complete the electrical connection of each negative pole tab 21 to the current collector 104 of the negative electrode of the battery cell 100, thereby improving assembly efficiency.

[0106] In a specific embodiment of the present application, the battery cell hot pressing and shaping device provided by the design includes a composite molding station 71, a die-cutting station 72, a winding station 73 and a shaping station 74 in sequence, as shown in FIG8 . Among them, the shaping station 74 heats the entire bare battery cell structure 40 by passing current through the negative electrode sheet 20 to generate ohmic heat. Therefore, in the die-cutting station 72, only the two negative electrode tabs 21 of the negative electrode sheet 20 electrically connected to the positive power supply 51 and the negative power supply 52 of the heating power supply 50 are die-cut to reserve the negative electrode tab electrical connection end 22. Moreover, in the shaping station 74, the first pressing plate 61 and the second pressing plate 62 are arranged vertically opposite each other. At this time, the first pressing plate 61 can be used as a supporting component for supporting the bare battery cell structure 40 in a fluffy state. Moreover, the driving mechanism is only connected to the second pressing plate 62, so that after the bare cell structure 40 is heated, the second pressing plate 62 is driven to move toward the first pressing plate 61 to clamp and shape the bare cell structure 40 to obtain a bare cell structure 40 with a fixed shape contour.

[0107] According to another aspect of the embodiments of the present application, a battery cell is provided, including a bare cell structure 40 that is hot-pressed and shaped using the aforementioned cell hot-pressing and shaping method, as shown in FIG9 .

[0108] In some embodiments of the present application, as shown in FIG9 , a battery cell 100 includes an end cap 101 , a housing 103 , a current collector 104 , at least one bare cell structure 40 , at least one enclosed liquid capsule 105 , and other functional components.

[0109] The end cap 101 refers to a component that covers the opening of the shell 103 to cover and seal the opening of the shell 103. Without limitation, the shape of the end cap 101 can be adapted to the shape of the shell 103 to match the shell 103. Optionally, the end cap 101 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 101 is not easily deformed when squeezed and collided, so that the battery cell 100 can have a higher structural strength and the safety performance can also be improved. Functional components such as electrode terminals 102 can be provided on the end cap 101. The electrode terminal 102 can be used to electrically connect to the bare cell structure 40 for outputting or inputting electrical energy of the battery cell 100. The material of the end cap 101 can also be various, including but not limited to copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0110] The shell 103 is a component used to cooperate with the end cover 101 to form an assembly space for the battery cell 100, wherein the formed assembly space can be used to accommodate the bare cell structure 40, electrolyte and other components. The shell 103 and the end cover 101 can be independent components, and an opening can be set on the shell 103, and the assembly space for the battery cell 100 is formed by covering the opening with the end cover 101. Specifically, the shape of the shell 103 can be determined according to the specific shape and size of the bare cell structure 40. The material of the shell 103 can be various, including but not limited to copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0111] When the end cap 101 and the shell 103 are made of conductive materials, an insulating layer needs to be provided on the inner wall of the assembly space formed by the end cap 101 and the shell 103 to avoid a short circuit between the end cap 101, the shell 103 and the bare cell structure 40, which may cause failure or damage to the battery cell 100.

[0112] At least one bare cell structure 40 is arranged in the housing 103, and the stacked positive electrode tabs 11 in the bare cell structure 40 are electrically connected via a current collector 104, and the stacked negative electrode tabs 21 are electrically connected via a current collector 104. Then, the current collector 104 electrically connected to the positive electrode tab 11 is electrically connected to the positive electrode terminal 102 provided on the end cap 101, and the current collector 104 electrically connected to the negative electrode tab 21 is electrically connected to the negative electrode terminal 102 provided on the end cap 101.

[0113] At least one enclosed liquid capsule 105 contains electrolyte. The liquid capsule 105 is disposed within the housing 103 and corresponds to at least one sidewall of the bare cell structure 40. The liquid capsule 105 is provided with at least one weakening structure. When the pressure within the liquid capsule 105 reaches a threshold, the electrolyte within the liquid capsule 105 breaks through the weakening structure and flows out of the liquid capsule 105.

[0114] The liquid capsule 105 is a closed capsule containing electrolyte and can deform when squeezed. To adapt to the internal usage environment of the battery and facilitate sealing, the liquid capsule 105 should be formed using a non-conductive packaging material with corrosion resistance and adhesiveness. For example, a functional composite film or packaging material comprising an external protective layer and an internal sealing layer can be used. The external protective layer is a corrosion-resistant insulating material that can be adapted to the electrolyte environment within the battery and adapt to the temperature, pressure and other environments under the battery's usage state. For example, the external protective layer can be made of aluminum, Teflon, acrylic, polypropylene, etc. The internal sealing layer can be, for example, a thermoplastic polyester film or coating that is convenient for packaging through a heat sealing process, such as polypropylene, polyvinyl chloride, polystyrene, acrylic resin, polycarbonate, polytetrafluoroethylene, polyurethane, etc. In some embodiments, an aluminum-plastic film can be used to form a closed liquid capsule 105 by heat sealing.

[0115] The liquid capsule 105 is provided with a weak structure, which has lower strength than other positions on the liquid capsule 105, so that when the pressure in the liquid capsule 105 reaches a threshold, the electrolyte will break through the weak structure and flow out of the liquid capsule 105 from the rupture of the weak structure.

[0116] “The side wall of the bare cell structure 40” refers to the outer wall of the bare cell structure 40 in the direction parallel to the height direction. The expansion force of the bare cell structure 40 is usually in the direction perpendicular to the height direction. Therefore, the bulging direction of the bare cell structure 40 mainly occurs in the large side wall (i.e., the thickness direction) and the corners (i.e., the two ends in the width direction). Making “the liquid capsule 105 at least corresponding to the side wall of the bare cell structure 40” means that the liquid capsule 105 is arranged in the shell 103 and at least part of the liquid capsule 105 is in contact with the side wall of the bare cell structure 40.

[0117] As the bare cell structure 40 is used for an extended period of time, when the sidewalls swell, an extrusion force is exerted on the liquid capsule 105 corresponding to the sidewalls of the bare cell structure 40. The liquid capsule 105 will be deformed by the extrusion, and will become thinner at the position corresponding to the sidewalls of the bare cell structure 40. The electrolyte in the liquid capsule 105 will be relatively concentrated in the area with less extrusion force, such as the end area of ​​the liquid capsule 105 along the height direction of the bare cell structure 40 in the figure, and this area will be used as a buffer space for the expansion force of the bare cell structure 40. At the same time, the internal pressure of the liquid capsule 105 increases, which has a certain resistance and relief on the expansion force of the sidewalls of the bare cell structure 40. In this way, the further deterioration of the expansion force of the bare cell structure 40 and the risk of lithium plating caused by squeezing the pole pieces can be avoided.

[0118] As the bare cell structure 40 continues to operate, the expansion force increases, further squeezing the sac 105. When the pressure inside the sac 105 reaches a threshold, the weak structure is breached, and the electrolyte in the sac 105 flows out of the sac 105 through the rupture at the weak structure. The electrolyte in the sac 105 automatically replenishes the electrolyte loss in the housing 103.

[0119] In a specific embodiment of the present application, the battery cell 100 provided by the design includes a liquid capsule 105 and two bare cell structures 40. In the housing 103, the liquid capsule 105 and the two bare cell structures 40 are stacked, and the liquid capsule 105 is located between the two bare cell structures 40.

[0120] The above are merely optional embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for hot pressing and shaping a battery cell, used for hot pressing and shaping a bare battery cell structure, characterized in that: The battery core hot pressing shaping method comprises the following steps: Electrically connecting two of the positive electrode tabs and / or two of the negative electrode tabs of the bare cell structure to a heating power source to electrically heat the bare cell structure; The heated bare cell structure is clamped and pressed to fix the shape of the bare cell structure.

2. The method for hot pressing and shaping a battery cell according to claim 1, characterized in that: Before executing the step of "electrically connecting two of the positive electrode tabs and / or two of the negative electrode tabs of the bare cell structure to a heating power source to electrically heat the bare cell structure", execute the steps of: stacking and composite-forming the positive electrode sheets, separators and negative electrode sheets into a cell material roll, and winding the cell material roll to form a bare cell structure.

3. The battery core hot pressing shaping method according to claim 1 or 2, characterized in that: During the process of executing the step of "electrically connecting two of the positive electrode tabs and / or two of the negative electrode tabs of the bare cell structure to a heating power source": two of the positive electrode tabs are the two positive electrode tabs that are farthest apart when the bare cell structure is unfolded into the cell material roll; and / or, two of the negative electrode tabs are the two negative electrode tabs that are farthest apart when the bare cell structure is unfolded into the cell material roll.

4. The battery core hot pressing shaping method according to claim 2 or 3, characterized in that: Before executing the step of "winding the battery core material to form a bare battery core structure", the two positive electrode tabs and / or the two negative electrode tabs that need to be connected to the heating power supply are die-cut to reserve the tab power connection ends.

5. The method for hot pressing and shaping a battery cell according to claim 4, characterized in that: When executing the step of "die-cutting the two positive pole tabs and / or the two negative pole tabs that need to be connected to the heating power supply to reserve the pole tab power connection ends", each of the positive pole tabs and each of the negative pole tabs are die-cut so that the contour shapes of each of the positive pole tabs and each of the negative pole tabs after die-cutting are consistent.

6. The method for hot pressing and shaping a battery cell according to any one of claims 2 to 5, characterized in that: During the process of executing the step of "winding the battery core material to form a bare battery core structure": the positive electrode tabs are aligned with each other, and there is a gap between the surfaces of two adjacent positive electrode tabs; and the negative electrode tabs are aligned with each other, and there is a gap between the surfaces of two adjacent negative electrode tabs.

7. The method for hot pressing and shaping a battery cell according to any one of claims 4 to 5, characterized in that: After completing the step of "clamping and shaping the heated bare cell structure", the electrical connection end of the tab is cut.

8. The method for hot pressing and shaping a battery cell according to any one of claims 1 to 7, characterized in that: During the execution of the step of "clamping and pressing the heated bare cell structure to shape it": the bare cell structure is clamped and pressed by means of upper and lower clamping.

9. The method for hot pressing and shaping a battery cell according to any one of claims 1 to 8, characterized in that: When executing the step of "electrically connecting two of the positive electrode tabs and / or two of the negative electrode tabs to a heating power source to electrically heat the bare battery cell structure", the heating time is 5s-10s.

10. The battery core hot pressing shaping method according to any one of claims 1 to 9, characterized in that: In the step "1", the heated bare cell structure is clamped and pressed to fix the shape of the bare cell structure. When the bare cell structure is formed into a "shape profile", the time for clamping the bare cell structure is 5s-10s.

11. The method for hot pressing and shaping a battery cell according to any one of claims 1 to 10, characterized in that: When executing the step of "clamping and pressing the heated bare cell structure to fix the shape contour of the bare cell structure", the surface pressure of clamping the bare cell structure is greater than or equal to 5 MPa.

12. The battery core hot pressing shaping method according to any one of claims 1 to 11, characterized in that: The interval time between executing the step of "electrically connecting two of the positive electrode tabs and / or two of the negative electrode tabs to a heating power source for electrical heating" and executing the step of "clamping and shaping the heated bare battery cell structure to fix the shape contour of the bare battery cell structure" is 0-10s.

13. A battery cell, characterized in that: It comprises a bare cell structure that is hot-pressed and shaped by the cell hot-pressing and shaping method as described in any one of claims 1 to 12.

14. A battery core hot pressing and shaping device, characterized in that: It includes a shaping station, which is provided with a driving mechanism, a first pressing plate, a second pressing plate and a heating power supply. The first pressing plate and the second pressing plate are arranged opposite to each other to clamp the bare battery cell structure. The driving mechanism is connected to the first pressing plate and / or the driving mechanism is connected to the second pressing plate. The heating power supply is used to electrically heat the bare battery cell structure.

15. The battery core hot pressing and shaping device according to claim 14, characterized in that: The battery cell hot pressing and shaping device also includes a winding station, which is located upstream of the shaping station and is used to wind the battery cell material to form the bare battery cell structure.

16. The battery core hot pressing and shaping device according to claim 15, characterized in that: The battery cell hot pressing and shaping device also includes a composite molding station and a die-cutting station. The die-cutting station is located upstream of the winding station, and the composite molding station is located upstream of the die-cutting station. The composite molding station is used to compositely mold the positive electrode sheet, the diaphragm and the negative electrode sheet into the battery cell material roll in a stacked manner. The die-cutting station is used to die-cut the positive electrode tabs and / or negative electrode tabs on the battery cell material roll, and die-cut to obtain the tab electrical connection ends for electrical connection to the heating power supply.

17. The battery core hot pressing and shaping device according to claim 16, characterized in that: The shaping station is further provided with a cutting mechanism, which is used to cut the electrical connection end of the tab after the first pressing plate and the second pressing plate clamp the bare battery core structure.

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